Operating mechanism for cover device



April 18, 1961 R. v. HARTY OPERATING MECHANISM FOR COVER DEVICE 3Sheets-Sheet 1 Filed Sept. 27. 1956 INVENTOR. 34/;72 #4 7'2? April 1 61R. v. HARTY 2,980,034

OPERATING MECHANISM FOR COVER DEVICE l INVENTOR.

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April 18, 1961 R. v. HARTY 2,980,034

OPERATING MECHANISM FOR COVER DEVICE Filed Sept. 27. 1956 3 Sheets-Sheet3 ,2; A L Y m n J INVENTOR.

- 7 fax/V514 United States a n I 2,980,034 OPERATING MECHANISM FOR COVERDEVICE Ralph Vincent Harty, 1433 Sloman Ave.,

Detroit 11, Mich.

Filed Sept. 27, 1956, Ser. No. 612,403

15 Claims. 015104-31 t This invention relates to operating mechanismsfor cover devices, and more particularly to a mechanism adapted for usein conjunction witha bridge for depressed railroad sidings.

Applicants copending application, Serial No. 505,907, filed May 4, 1955,now Patent No; 2,889,565, dated June 9, 1956, entitled Lift Bridge,describes a bridge for use in suchplaces as factory buildings which havea depressed railroad siding or spur line cutting through the factoryfloor. This bridge carries a plurality of short track sec tions whichare contiguous with the siding tracks when the bridge is in its loweredposition, and a deck structure which is at the same level as theplatforms on both sides of the siding when the bridge is in its raisedposition. The bridge is thus capable ofcarrying factory floor traflicacross the railroad siding when the latter is not in use, and permitsuse of the railroad tracks when lowered.

It is an object of the present invention to provide a novel and improvedcover device and operating mechanism therefor, which will conceal andcover the rail sections of such a bridge when the bridge is in itsraised position, thereby creating a continuously smooth deck surfaceacross the entire bridge, facilitating the transportation of trucks andthe general how of trafic and eliminating the hazards to such trafficwhich would otherwise be presented by gaps between the rail sections andthe adjacent edges of the bridge decking.

It is another object to provide an improved cover operating mechanism ofthe above nature which will automatically retract the rail cover whenthe bridge is lowered so that the rail section may be utilized, and willmove the cover into its operative position in' response to raising ofthe bridge, without the necessity for a separate driving mechanism orfor any manipulations by the bridge operator other than those involvedin raising and lowering the bridge.

It is a further object to provide an improved rail cover operatingmechanism having the above characteristics, which may be entirelyconcealed within the bridge structure itself, and which is of relativelysimple construction requiring little or no maintenance expense.

Other objects, features and advantages of the present invention willbecome apparent 'from the subsequent description, taken in conjunctionwith the accompanying drawings.

in the drawings:

Figure 1 is a perspective view of a bridge of the type to which thecover operating mechanism of this invention is to be applied, showingthe bridge in its raised position with the rail covers concealing therails and flush with the bridge decking;

Figure 2 is a fragmentary plan view of a portion of the bridge showingthe configuration of a single rail cover;

Figure 3 is a partially schematic elevational view taken in crosssection along the line 3-3 of Figure 2 and showing the cover mechanismwith the cover in operative position? Figu e 4 is a view similar toFigure 3 showing the P Patented Apr. 18, 1961 'icc mechanism when thebridge is in its lower position and the cover retracted;

Figure 5 is an end elevational view taken in cross section along theline 5-5 of Figure 2 and showing the two guide tracks and a portion ofthe supporting structure for the mechanism;

Figure 6 is assembly; I

' Figure 7 is a plan view of the roller assembly; and Figure 8 is adetailed view in elevation of oneof the guide tracks. a

In general terms, the invention comprises a mechanism for use with anelongated flatcover which, when in operative position, overlies a railsectionon a bridge of the type described above. As many covers will bemounted on the bridge as there are rail sections, each cover having itsown operating mechanism. Each mechanism is disposed, within acompartment inside the bridge and below the levelof the bridge decking,this compartment being laterally adjacent the rail section. In view ofthe length of the rail cover which will normally be required, two

' or more identical operating mechanisms may be provided atspacedpointsalong the cover, thus facilitating movement of the cover betweenits operativeand retracted positions, and the compartments containingthese separate mechanisms will thus be spaced from each other in thedirectionof extent vof the rail.

Each. operating mechanism comprises a linkage ar rangement disposedwithin one of said compartments, said linkage arrangement beingconnected with a fiat plate which is attached to and flush with thecover plate and extends laterally therefrom. The bridge decking adjacentthe rail is cut out to accommodate this extension plate, so that thecover plate with its extensions may move as a unit between a retractedposition and an oper ative position flush with the bridge decking. Thelinkage arrangement is such that upon lowering of the bridge, the coverplate assembly will first be lifted out of the plane of the bridgedecking and will then be retracted in a direction transverse to the railuntil the latter is uncovered, the cover assembly resting on theadjacent bridge decking when in retracted position. The rail sectionwill thus be exposed for use as long as the bridge is in its lowerposition. When the bridge is raised, the operating mecha-' nism willautomatically move the cover assembly in the opposite direction until itis directly over its corresponding gap in the bridge decking, and willthen cause the cover assembly to be lowered into flush relationship withthe decking. A smooth and substantially unbroken decking will thus beprovided over the entire bridge, facilitating factory floor trafficacross the railroad siding.

Referring now in detail to the drawings, Figure 1 shows a bridgegenerally indicated at 11 which is disposed within a depressed railroadsiding or spur line 12, the platforms alongside the spur line beingdesignated 13 and 14 respectively. The bridge is provided with four railsections 15, 16, 17 and 18 which are adapted to be aligned with twopairs of rails 19 and 21 respectively when the bridge is in its lowerposition, permitting the use of siding 12 for railroad cars. The uppersurface of the bridge is provided with a plurality of deck plates 22,23, 24, 25 and .26 between which rails 15-18 are disposed. These deckplates are in a plane immediately above the tops of rails 15-18, andWhen'bridgell is in its raised position are flush with platforms 13 and14 alongside railroad siding 12, thus facilitating factory floor trafiicacross the siding.

In order to provide flush connecting surfaces between deck plates 22-26,four cover assemblies generally desig nated 27, 28, 2.9 and 31 areprovided for rails 15-18 re spectively. When bridge 11is in its raisedposition, these cover assemblies will be in overlying relation withtheir corresponding, rails and in flush relation with the deck adetailed elevational view of the roller m it plates of the bridge, thusproviding a smooth surface unbroken by gaps between the deck plates.When the bridge is lowered, cover assemblies 27-31 will be retractedlaterally with respect to their rails, exposing the latter for use andresting on the adjacent portions of the bridge decking.

Each of cover assemblies 27 3-1 comprises an elongated fiat cover plate32 for the rail, and a plurality of extension plates 33 secured to andextending laterally from cover plate 32. As seen best in Figure 2, twosuch extension plates 33 are provided for each cover plate in theillustrated embodiment, although a diiferent number could be provided inaccordance with requirements. As .described below in detail, theoperating mechanism associated with each extension plate 33 is disposedbelow such plate and within bridge 11. In the embodiment of the liftbridge described in the aforementioned copending application, thelifting mechanism for the bridge, such as a pair of pistons andcylinders, is disposed below the central portion thereof, that is belowdeck plate 24 shown in Figure 1. Such means is indicated by dotted linesat 24a in Figure 1. The operating mechanisms for the rail coverassemblies are therefore suitably disposed below deck plates 22, 23, 25and 26 respectively. For this reason, extension plates 33 of the coverassemblies are shown in Figure l as extending into rectangular cutouts34 provided in plates 22, 23, 25 and 26 so that the operating mechanismsmay be conveniently connected to the extension plates. It should beunderstood however that other locations for the cover operatingmechanisms could be provided within the principles of the invention,depending upon the construction of the particular bridge and itsassociated parts.

As seen best in Figure 2, cover plate 32 of a typical cover assembly 27is adapted to fit between the opposing edges 35 and 36 of deck plates 22and 23 respectively, with extension plates 33 secured to plate 32 atspaced portions of the edge 37 thereof adjacent deck edge 35.Compartments 38 and 39 respectively are provided below extension plates33 to enclose the cover operating mechanisms. A single cover operatingmechanism is shown in Figures 3, 4 and 5 and is disposed between a pairof upright side plates 41 and 42 and channel-shaped beams 43 and 44supported by plates 41 and 42 respectively. As seen in Figure 5, thesebeams support a pair of bed plates 45 and 46 respectively on which restthe adjacent edges of deck plate 22. Bed plates 45 and 46 extendinwardly from channels 43- and 44 respectively and serve to support theouter portions of extension plate 33, as seen in Figure 5, when coverassembly 27 is in its operative position.. A pair of deck supportingbeams 47 and 48 extend alongside rail 15, being supported by the outerportions of an I beam 49' which also supports rail 15. Beams 47 and 48serve to support edges 35 and 36 of deck plates 22 and 23 respectively.A shorter beam 50 may also be provided for supporting that portion ofdeck plate 22 adjacent the outer end of extension plate 33-. Beam 50 maybe supported by some appropriate portion 51 of the understructure ofbridge 11.

Secured to the underside of each extension plate 33 is a roller assemblygenerally indicated at 52, the details of this assembly being best seenin Figures 6 and 7. Assembly 52 comprises a pair of plates 53 and 54 inspaced parallel relation, the upper edges 55 of these plates beingwelded or otherwise secured to the undersurface of extension plate 33 insuch a manner that plates 53 and 54 extend at right angles to coverplate 32. Apair of shafts 56 and 57 are supported between plates 53- and54. Shaft 56 extends outwardly from said plates and carries a pair ofrollers 58 and 59 at the outer ends thereof. Shaft 57 is supported by apair of downwardly extending arms 61 on plates 53 and 54 at the end ofsaid plates remote from shaft 56. Shaft 57 carries a pair of rollers apair of spacers 64 and 65. respectively. Rotatably mounted on shaft 57between rollers 62 and 63 is a sleeve 66 to which are secured the upperends of a pair of identical levers 67, these levers operating in unisonas described below.

It will be noted from an examination of Figure 6 that the axis ofrollers 62 and 63 is somewhat below that of rollers 58 and 59, and thatrollers 62 and 63 are of somewhat larger diameter than the other pair ofrollers. It shouldalso be observed that both pairs of rollers are sodisposed that their lower portions extend below the lower edges ofplates 53 and 54, and that rollers 62 and 63 also extend beyond verticalside edges 68 of arms 61. It should be noted that because of theconfiguration of the cover assembly as seen in Figure 2, the center ofgravity of the cover assembly will be a substantial distance to theright of rollers 62 and 63, as seen in Figures 3 and 4.

Rollers 58 and 59 as well as rollers 62 and 63 are adapted to cooperatewith a pair of tracks generally indicated at 69 and 71 respectively,these tracks being secured to beams 43 and 44 respectively within thebridge compartment. The construction of each track is shown best inFigures 5 and 8, and comprises an angular member one leg 72 of which issecured to beam 43 or 44, with the other leg 73 extending horizontallytherefrom. A block 74 is secured to the upper surface of leg 73, thisblock having an inclined surface 75 and a horizontal surface 76 andextending partway along leg 73, so that these two surfaces combine witha lower horizontal surface 77 on leg 73 to form a ramp having an upperhorizontal surface 76 relatively close to rail 15, a downwardly inclinedsurface 75 extending away from surface 76 and a lower horizontal surface77 relatively remote from rail 15. Leg 73 and block 74 combine topresent a forward surface '78 which is so located that, when coverassembly 27 is in its operative position as shown in Figure 3, surface78 will be immediately adjacent that portion of roller 62 or 63extending beyond edge 68 of arm 61. This relationship between verticalsurfaces 78 of the two guide tracks and rollers 62 and 63 is best seenin Figure 3, and it will be noted from this figure that leftwardmovement of cover assembly 27 will be prevented until rollers 62 and 63are lifted above surfaces 78. It should also be observed that whenrollers 62 and 63 are in the position shown in Figure 3, rollers 58 and59 will engage surface 76 of the tracks, this engagement servingpartially to support cover assembly 27 in its operative position.Additional supporting strips 79 and 81 secured to the undersides of theedges of deck plate 22 may also be provided for supporting coverassembly 27, and a supporting strip 82 secured to beam 48 adjacent rail15 may also serve this purpose. Surfaces 76 of tracks 69 and 71 are atsuch a height that when rollers 62 and 6.3 are lifted so as to restthereon, that portion of cover assembly 27 which is also lifted will beabove the level of deck plate 22. More specifically, since the center ofgravity of cover assembly 27 is to the right of rollers 62 and 63,lifting of these rollers will cause the left hand ends of extensionplates '33, as seen in Figures 3 and 4, to be lifted until they areclear of deck plate 22, cover assembly 27 temporarily assuming anangular position as partially indicated by dot-dash lines in Figure 3.The height of horizontal surfaces 77 of tracks 69' and 71 are such thatwhen rollers 62 and 63 approach these surfaces the lower surface ofcover assembly '27 will come to rest upon the upper surface of deckplate 22, as seen in Figure 4, the cover assembly thus returning to ahorizontal position.

The means for moving cover assembly 27 between its positions includes abell crank 83 mounted on a pivot 84 fixed to the bridge structure andhaving one arm 85 to which the lower ends of levers 67 are pivotallysecured. Pivoted to the other arm 86 of bell crank 83 is a yoke 87, theother end of the yoke carrying a slot 88 8 within which is disposed apin 89 fixed to lever-s67 atan intermediate portion thereof but closerto the upper ends of the levers. A link 91 is pivoted at one end to anintermediate portion of yoke 87 and at its other end to one arm 92 of abell crank 93 which is on a pivot 94 fixed to the bridge structure. Theother arm 95 of hell crank 93 is secured to one end of a chain 96 orsimilar flexible connection, the lower end .of the chain being fixed toa stationary portion 97 of the structure which does not move with thebridge. A stationary projection 98, which likewise is not attached tobridge 11, is disposedbetween arm 95 of hell crank 93 and the lower endof chain 96. The disposition of stationary projection 98 is such thatwhen bridge-11 is lowered with bell crank 93 in the position shown inFigure 3, arm 95 of bell crank 93 will engage projection 98, causingrotation of the bell crank into its counterclockwise position as shownin Figure 4. In describing the operation of the device, it will beassumed that bridge 11 is initially in its raised position connectingplatforms 13 and 14, that it is lowered to position rails '15-18 inalignment with rail pairs 19 and 21 for passage of railroad cars, andthat it is thereafter again raised to its original position. Throughoutthis cycle of operations, cover assemblies 27-31 will perform similarmovements with respect to their corresponding rail sections 1'5-18, andthe operating mechanisms beneath all cover extensionplates 33'willlikewise perform identical functions. Therefore, the operation of coverassembly 27 and of one of thetwooperating mechanisms associatedtherewith need only be described. When When bridge 11 is lifted, theparts will remain in the position shown in Figure 4 until chain 96becomes taut. When this occurs, bell crank 93 will be swung clockwise,and link 91 will transmit a rightward force component to'yoke 87. Thelower end of the yoke will tend to rotate bell crank 83 clockwise asshown in Figure 4, but this movement will be resisted by the engagementof rollers 62- and 63 with tracks 69 and 71. The upper end of yoke 87will urge the upper portions of levers 67 to the right, and coverassembly 27 will be moved righwardlyas rollers 62 and 63 rollv upinclined surfaces 75 of tracks .69 and 71. This movement will continueuntil rollers 62 and. 63 reach the ends of track surfaces bridge 11 isin its raised position, cover assembly 27 will .be in the position shownin Figure 3, flush with deck plates 22 and 23 and concealing rail 15.Rollers 58 and 59 will rest upon surfaces 76 of tracks 69 and 71, andthe edges of cover assembly 27 will be supported by strips 79, 81 and82. Rollers 62 and 63 will be in engagement with vertical surfaces 78 oftracks 69 and 71, with levers 67 in a substantially vertical position,pin 89 in the bottom portion of yoke slot 88, and chain 96 relativelytaut with arm 95 of hell crank 93 some distance above stationaryprojection 98. When bridge 11 is lowered, pivots 84 and 94 attached tothe bridge will likewise be lowered. Arm 95 of bell crank 93 will engagestationary projection 98, and further downward movement of pivot 94 willcause bell crank 93 to rotate counterclockwise as seen in Figure 3. Thiswill cause link 91 to be pulled to the left, creating a leftward forceon both ends of yoke 87. The upper slotted end of yoke 87 will tend tourge pin 89 to the left, but since vertical track surfaces 78 are inobstructing relation with rollers 62 and 63, this movement will not bepermitted. The lower end of yoke 87 will rotate bell crank 83counterclockwise as seen in Figure 3, thus creating a substantiallyvertical force on levers 67. This force will be transmitted throughroller assembly52 to cover assembly 27. Since the center of gravity ofthe cover assembly is to the right of rollers 62 and 63, the left handportions of cover assembly 27 will be lifted, resulting in the outerends of extension plates 23 clearing of deck plate 22.

This lifting mo ement will continue until rollers 62 and 63 clearvertical surfaces 78 of tracks 69 and 71. When this occurs, horizontalforce components transmitted from yoke 87 to pin 89 (the latter havingmeanwhile moved to the upper portion of slot 88) will cause coverassembly 27 to be moved to the left into the position shown in Figure 4.During this movement, rollers 62 and 63 will roll along track surfaces76'and down track surfaces '75, arriving at surfaces 77 in whichposition cover assembly 27 will rest on deck plate 22, leaving rail 15exposed. Because of the inclined nature of track surfaces 75, there willbe no tendency for cover assembly 27 to move toward rail 15 while thebridge is in its lower position, and there will thus'be no danger ofinterference with railroad cars running along the rails.

76, Whereuponthe rollers will drop into the position shown in Figure 3in front of vertical surfaces 78. This will cause cover assembly 27 tobe lowered into its operative position flush with deck plates 22 and 23.It should be noted that the movement of cover assembly 27 into its flushor operative position is positive, since bell crank 83 will be urgedclockwise by yoke ,87 and will therefore'pull levers 67 downwardly. Allmovements of the cover assemblies between their operative and-retractedpositions will thus be accomplished automatically and simultaneouslywithout the necessity of the operator attending to any controls otherthan those used for raising .and lowering the bridge.

While it will be apparent that the preferred embodiment of the inventiondisclosed is well calculated to fulfill the objects above stated, itwill be appreciatedthat the invention is susceptible to modification,variation and change without departing from the proper scope or fairmeaning of the subjoined claims.

What is claimed is:

'1. In a vertically movable bridge for use in conjunction with adepressed railroad siding having platforms therealong, a plurality ofdeck plates on said bridge positioned for use as part of a deck, saiddeck plates being substantially flush with the platforms alongside saidsiding when the bridge is in its raised position, said deck plates beingspaced apart horizontally to provide gaps therebetween, said gap beingaligned with the tracks of said railroad siding, rails disposed withinsaid gaps and adapted to be aligned with the rails of said siding whensaid bridge is in its lower position, covers for said gaps movablebetween an operative position covering said gaps and a retractedposition exposing said rails, and means mounted on said bridgeresponsive to movement of said bridge to its raised position for movingsaid covers to their operative position and responsive to movement ofsaid bridge to its lower position for moving said covers to theirretracted position.

2. In combination, a bridge movable between a lower position and anupper position, a pair of deck plates on said bridge in substantiallythe same plane and positioned for use as part of a deck when said bridgeis in one of said positions, said deck plates being spaced apart with agap therebetween, said gap being transverse to the extent of the bridge,a cover plate-for said gap, said cover plate being movable between anoperative position covering said gap and in the same plane as said deckplates to form a continuous deck, and a retracted position to one sideof said gap and out of said plane, means mounted on said bridgeresponsive to movement of said bridge from said one position to theother position for first moving said cover plate out of said plane andthen moving the cover plate to one side of said gap, and means mountedon said bridge responsive to movement of said bridge to said oneposition for first moving said cover plate into alignment with said gapand then into the plane of said deck plates.

.3. In a vertically movable bridge for use in conjunction with adepressed railroad siding having platforms along the sides thereof, aplurality of deck plates on said bridgein substantially the same planeand positioned anemone i to connect the platforms alongside said sidingwhen the bridge is in its raised position, said deck plates being spacedapart to provide gaps therebetween extending in the direction of andaligned with the siding rails, a plurality of rail sections mounted onsaid bridge below the level of said deck plates, said rails beingaligned with said gaps and adapted to be aligned with the siding railswhen said bridge is in its lower position, a plurality of elongatedcover plates movable between an operative position covering said gapsand in the plane of said deck plates, and a retracted position exposingsaid rails and alongside said gaps above said deck plates, a transverseextension on each of said cover plates, cutouts in said deck platesadjacent said gaps for accommodating said extensions when said coverplates are in their operative position, and operating means for saidcover plates disposed below the level of said deck plates and connectedto said extensions, said operating means being responsive to movement ofsaid bridge to its lower position for first lifting said cover platesand extensions above the plane of said deck plates and then moving saidcover plates and extensions to their retracted position, said operatingmeans being further responsive to movement of said bridge to its upperposition for first moving said cover plates and extension into alignmentwith said gaps and cutouts and then moving said cover plates andextensions to their operative position.

4. In a bridge, means for moving said bridge between an upper positionand a lower position, a pair of spaced plates on said bridge positionedfor use as part of a deck and having a gap therebetween, said gap beingtransverse to the extent of the bridge, a cover for said gap movablebetween an operative position covering said gap and contiguous with saidplates when said bridge is in one of its positions, and a retractedposition to one side of said gap and above one of said plates when saidbridge is in its other position, an operating mechanism for said coverincluding a lever connected to the underside of said cover and extendingtherebelow, the point of connection of said lever to said cover beingspaced from the center of gravity of said cover in a direction towardsaid one side of the gap, means for simultaneously applying upward andlateral forces to the upper end of said lever when said cover is in itsoperative position, and means for restraining said cover against lateralmovement only until the side of said cover toward said one side of thegap has been lifted to a height above said one plate, whereby saidlateral force will be effective after said height has been reached tomove said cover to its retracted position.

5. The combination according to claim 4, said restraining meanscomprising a substantially vertical obstructing surface, an elementconnected to said cover and engageable with said vertical surface, asubstantially horizontal surface engageable by said element afterlateral retracting movement of said cover has been initiated, and meansfor applying a lateral force to said cover opposite to said firstlateral force, whereby said cover element will be moved along saidhorizontal surface to the end thereof and will then drop in front ofsaid vertical surface, the cover thereby being moved to its operativeposition.

6. In a bridge, means for moving said bridge between an upper positionand a lower position, a pair of spaced plates on said bridge having agap therebetween and positioned for use as part of a deck, said gapbeing transverse to the extent of the bridge, a cover for said gapmovable between an operative position covering said gap and contiguouswith said plate when said bridge is in one of its positions, and aretracted'position to one side of said gap and above one of said plateswhen said bridge is in its other position, a lateral extension plate onand extending from said cover, a cutout in said one plate foraccommodating said extension plate 8: when said cover is in itsoperative position, a pairof rollers mounted on a horizontal axis belowand secured to said extension plate, a pair of stationary tracks forcooperation with said rollers, said tracks having substantially verticalsurfaces facing said gap and horizontal surfaces extending laterallyfrom the upper ends of said vertical surfaces at a height such that,when said rollers rest on said horizontal surfaces, the outer end ofsaid extension plate will be above the level of said one plate, a leverconnected to the underside of said extension plate adjacent said rollersand extending therebelow, and means for simultaneously applying upwardand lateral forces to the upper end of said lever when said cover is inits operative position, the disposition of said vertical track surfacesbeing such that said rollers will be restrained against lateral movementuntil said rollers reach said horizontal track surfaces, whereby theouter end of saidextension plate will first be lifted above said oneplate and said cover will then be moved to its retracted position.

7. The combination according to claim 6, said means for simultaneouslyapplying upward and lateral forces comprising a yoke, a slottedconnection between one end of said yokeand the upper end of said lever,a bell crank connection between the opposite end of said yoke and thelower end of said lever, and means for applying a lateral force to anintermediate portion of said yoke.

8. The combination according to claim 6, further pro vided withdownwardly'inclined track portions at the ends of said horizontal tracksurfaces remote from said vertical surfaces, and a second pair ofhorizontal track surfaces extending from the lower ends of said inclinedsurfaces, the height of said second pair of horizontal track surfacesbeing such that engagement of said rollers therewith will bring theunderside of said cover into engagement with the upper surface of saidone plate.

9. The combination according to claim 6, further provided with a secondpair of rollers supported beneath said extension plate on an axisparallel to said first roller axis, said second pair of rollers beingengageable with said pair of horizontal track surfaces when said coveris in its operative position.

10. In a cover operating device for installation on a ertically movablebridge, a cover means on said bridge responsive to movement of saidbridge in one direction for moving said cover from a first position to asecond position out of the plane of and to one side of said firstposition, and means on said bridge responsive to movement of said bridgein the opposite direction for moving said cover from its second positionto its first position.

11. In a cover operating device or installation on a vertically movablebridge, a cover, a lever having an upper end adapted for operativeconnection to said cover,

said upper end being movable between a first position and a secondposition vertically and horizontally displaced from said first position,an actuating link movable in opposite directions, operating meansconnecting one end of said link to said lever in'such manner thatmovement of said link in one direction will cause the upper end of saidlever to move from its first to its second position and movement of saidlink in the opposite direction will cause the upper end of said lever tomove from its second to its first position, a bell crank pivoted on saidvertically movable bridge, a pivotal connection between one arm of saidbell crank and the other end of said link, a stationary elementengageable by the other arm of said bell crank when said bridge moves inone direction, whereby force will be applied to said link in onedirection, and a chain having one end stationarily fastened and theother end connected to said other bell crank arm, whereby movement ofsaid bridge in the opposite direction will cause a force to be exertedon said link in the opposite direction. i

9 to 12. In a bridge, means for moving said bridge between an upperposition and a lower position, a pair of deck plates on said bridgepositioned for use as part of a deck, said deck plates being spacedapart leaving a gap therebetween, said gap being transverse to theextent of the bridge, a cover plate movable between an opera-- tiveposition covering said gap to form a continuous deck and a retractedposition exposing said gap, means mounted on said bridge responsive tomovement of said bridge from one of said positions to the other positionfor moving said cover plate to its retracted position, and means mountedon said bridge responsive tomovement of said bridge from said otherposition to said one position for moving said cover plate to itsoperative position.

13. In a bridge, means for moving said bridge between an upper positionand a lower position, a pair of horizontally spaced plates on saidbridge having a gap therebetween and positioned for use as part of adeck, said gap being transverse to the extent of the bridge, a cover forsaid gap movable between an operative position covering said gap andcontiguous with said plates when said bridge is in one of saidpositions, and a retracted position to one side of said gap and aboveone of said plates when said bridge is in its other position, anoperating mechanism for said cover mounted on said bridge includingmeans for simultaneously applying upward and lateral forces to saidcover when said cover is in its operative position, and means forrestraining said cover against lateral movement only until said coverhas been lifted to a height above said one plate, whereby said lateralforce will be effective after said height has been reached to move saidcover to its retracted position.

14. In a bridge, means for moving said bridge between an upper positionand a lower position, a pair of spaced plates on said bridge having agap therebetween and positioned for use as part of a deck, said gapbeing transverse to the extent of the bridge, a cover for said gapmovable between an operative position covering said gap and contiguouswith said plates when said bridge is in one of said positions, and aretracted position to one side of said gap and above one of said plateswhen said bridge is in its other position, a lever pivotally connectedto the underside of said cover and extending therebelow, means forsimultaneously applying an upward force to the lower end of said leverand a lateral force to the upper end of said lever when said cover is inits operative position, a vertical obstructing surface below said cover,and an element connected to said cover and adapted to be obstructed bysaid surface only until said cover has been raised a predetermineddistance, whereby continued application of said lateral force to saidlever will cause movement of said cover to its retracted position. v

15. In a bridge, means for moving said bridge between an upper positionand a lower position, a pair of spaced plates on said bridge having agap therebetween and positioned for use as part of a deck, said gapbeing transverse to the extent of the bridge, a cover for said gapmovable between an operative position covering said gap and contiguouswith said plates when said 'bridge is in one of its positions, and aretracted position to one side of said gap and above one of said plateswhen said bridge is in its other position, a roller secured to theunderside of said cover on a horizontal axis transverse to the directionof cover movement, a station'- pivoted to the underside of said rollerand extending therebelow, a bell crank on a stationary pivot, a pivotalconnection between one arm of said bell crank and the lower end of saidlever, a yoke, a pivotal connection between the other arm of said bellcrank and one end of said yoke, a pin-and-slot connection between theother end of said yoke and an intermediate portion of said lever, andmeans connected to said yoke for exerting a transverse force on anintermediate portion of said yoke in opposite directions, whereby atransverse force ap plied in one direction will cause upward and thenlateral movement of said cover into its second position, and applicationof the opposite transverse force to said yoke will cause lateral andthen downward movement of said cover into its first position.

References Cited in the file of this patent UNITED STATES PATENTS912,019 Maulty Feb. 9, 1909 1,015,793 Eldridge Jan. 30, 1912 2,271,697Lefiler et al. Feb. 3, 1942 r 2,381,966 Bishop et al. Aug. 14, 19452,482,562 Shoemaker Sept. 20, 1949 2,489,869 Dunn NOV. 29, 19492,652,783 Skinner Sept. 22, 1953 2,750,135 Anderson June 12, 1956

